1. Field of Invention
This invention relates generally to gun-type dispensers for discharging a viscous fluid or paste, such as a sealing or bonding agent, from a container storing this agent, and in particular to a double-barreled epoxy injection gun in which the two components of the epoxy are stored in separate foil packs that are loaded into the parallel barrels of the gun, the gun functioning to slit open the packs to permit extrusion and intermingling of the components to form the epoxy.
2. Status of Prior Art
Caulking is a putty-like plastic compound used for filling joints between masonry and other building materials, and for sealing cracks around window frames and wood and metal elements built into masonry joints. Caulking is usually applied by extruding it from a caulking gun to form a bead along the joint.
Caulking compounds and other pastes and viscous fluids which are to be dispensed from a gun are normally stored in a rigid cylinder having a sealed spout projecting from its forward end, the base of the cylinder being defined by a plunger. After the sealed spout is cut open, the plunger is advanced to subject the contents of the container to pressure, thereby causing the viscous fluid or paste to be extruded from the open spout.
Since it is necessary by means of a razor or scissor to cut open the spout, the viscous fluid in the container may then leak from the open spout and soil the hands of the operator as well as otherwise clean surfaces.
In order to provide a grease-dispensing gun adapted to be refilled and operated without soiling the hands of the operator, the Switzer patent, U.S. Pat. No. 2,733,836, discloses a gun whose barrel is loaded with a sealed cylindrical cartridge containing grease. The Switzer gun includes at its forward end a piercing point that when the cartridge is subjected to pressure by a hand-operated plunger, punctures an opening in the cartridge.
In the Meyers et al. U.S. Pat. No. 3,130,872, the dispensing gun is adapted to discharge oils and other viscous fluid contained in sealed metal cans, and for this purpose, a spout is mounted on the front end of the gun, the spout having at its rear end a piercing point. When the can is pressed thereagainst by a hand-operated ram, the point punctures an opening therein into which the spout is inserted, so that the oil contends of the can may now be discharged.
In the dispensing gun shown in the Isgriggs et al. U.S. Pat. No. 3,193,146, a sealed can containing oil is loaded into the barrel of the gun whose forward end is provided with a slidable tap terminating in a piercing point. A removable plug received in the tap is struck a blow to cause the can to be pierced, after which the plug is removed to permit flow of the oil from the tap when pressure is applied to the can.
The concern of the present invention is not limited to gun-type dispensers for single component viscous fluids or pastes, for a need also exists for dispensers of two-component compounds such as an epoxy bonding agent in which one component is an epoxy resin and the other a hardener therefor. Separate packages are required for the components which are only intermixed when the epoxy is to be applied to a site to be bonded.
A problem which arises when the two components of an epoxy bonding agent are contained in separate squeeze tubes each having a sealed spout, is that if the same razor or other cutter is used to cut open both spouts, then the surface of the cutter may become smeared with both components which will interact and bond to this surface.
The Creighton et al. U.S. Pat. No. 3,323,682 discloses a gun-type dispenser in which two cartridges separately storing the resin and catalyst or hardener components of an epoxy bonding agent are concurrently subjected to pressure to extrude these components from the cartridges. As pointed out in this patent, should the resin and hardener components be accidentally mixed together in advance of their intended use, curing will then take place prematurely in a relatively short time, and the resultant epoxy would not be usable. It is essential, therefore, that the epoxy components be stored in separate sealed containers.
In the present invention, the viscous fluid paste to be dispensed is stored in a squeezable sealed pouch. Of prior art interest in regard to a pouch of this type is the Wainberg U.S. Pat. No. 4,265,372, in which oil or other viscous fluid is contained in a pouch formed of synthetic plastic material. This pouch is loaded into a dispenser-cutter which includes a blade that punctures a hole in the pouch which is then subjected to pressure to discharge the contents from the hole.
If one were to load a pouch of the Wainberg et al. type into the barrel of a dispensing gun and pierce an opening in the front end of the pouch, then when the pouch is subjected to pressure to extrude its contents, this will result in an exhausted pouch in a collapsed state at the front end of the barrel. And because the pouch in this state is crushed or crumpled, it is then more or less frictionally stuck within the barrel.
Yet in order to reload the barrel it is necessary to first pull out the crushed pouch therefrom. If an operator seeks to use his fingers for this purpose, he will not only experience difficulty in doing so, but he is likely to soil his fingers, for the surface of the collapsed pouch surrounding its pierced opening is smeared with the constituent it contained. Should he instead use a tweezer or other tool to extract the collapsed pouch from the barrel, the tool will become smeared. And if the gun has a pair of barrels, one for each component of an epoxy resin, since these components interact quickly, should the tool be smeared with both components, an epoxy will form and harden on the surface of the tool which will then be difficult to clean.
Also of prior art interest is the patent to Cannon et al., U.S. Pat. No. 3,767,085, showing a double barrel syringe having a common mixing chamber. Received in the barrels are cartridges containing the two constituents to be mixed, each cartridge having a rear plug which is engaged by a piston. The rods of the two pistons are joined by a common handle for concurrent advance of the pistons.